Apparatus for attaching a disk to a spindle of a spinstand, methods for attaching and detaching a disk to and from a spindle of a spinstand and a movable stage

ABSTRACT

In one arrangement, apparatus for attaching a disk to a spindle of a spinstand has a spindle adapter. The spindle adapter has a drawbar movably disposed within. The drawbar has a connector end that is reversibly connectable to the cap and has a piston that is connectable to a source of fluid pressure. The drawbar is movable in response to fluid pressure so as to urge together the cap and the spindle adapter when connected. The cap and the spindle adapter are capable of holding a said disk therebetween. In another arrangement, a movable stage movable over a deck of a spinstand has a lift stage arranged to hold a cap with a disk positioned thereon. The lift stage has at least one actuator for raising the lift stage so that the cap can be connected with a spindle adapter of an inverted spindle of a spinstand.

TECHNICAL FIELD

The present invention relates to apparatus for attaching a disk to aspindle of a spinstand, methods for attaching and detaching a disk toand from a spindle of a spinstand, and a movable stage.

BACKGROUND

It is well known to use a spinstand to test various components of a harddisk assembly, such as in particular the read/write heads and the diskmedia. Such tests can be carried out in a manufacturing productionenvironment, where typically every head and a proportion of disks aretested prior to being assembled into a hard disk assembly to ensure thatthey perform to the required standard. Testing using a spinstand canalso be carried out in a research and development setting.

A spinstand typically comprises a deck, for example of granite, which isgenerally isolated from external sources of vibration in some way toavoid these affecting the accuracy of the test results. A spindle isattached to the deck for holding and rotating the disk. This willtypically be an air bearing spindle with an integrated DC brushlessmotor. The spinstand has a puck for receiving the read/write head. Thepuck is positionable so as to move the head to a desired location underthe surface of the disk. The puck will typically be positionable by ahighly accurate x-y positional stage, having air bearings and linearencoders. It may also be possible to lock the puck down to the graniteby application of a vacuum in order to prevent movement of the puck whenin a desired position. The puck generally has some arrangement forloading/unloading the head to/from the test surface of the disk, suchthat the head can read and/or write a track of test data from the testsurface of the disk. The puck also generally has some arrangement, suchas a nanopositioner, for making very fine positional changes of the headrelative to the test track.

When testing disks with a spinstand, particularly in a manufacturingenvironment, it is desirable to be able to swap the disk under test fora new disk as quickly and dependably as possible. It is also desirableto accelerate and decelerate the disk under test as fast as possible inorder to increase throughput of disks tested. High accuracy inpositioning the disk is also required. However prior art arrangementsfor attaching the disk to the spindle present many disadvantages inachieving these aims.

Another important consideration in attaching the disk to the spindle isaccurately and dependably setting the so-called z-height of the testsurface of the disk, i.e. the vertical height of the test surfacerelative to a datum or reference position. This is because, when loadinga read/write head to a disk, the head must be vertically positioned withgreat accuracy relative to the test surface of the disk and so it isimportant that the z-height of the test surface is closely controlledwhen loading the disk to the apparatus. The maximum variation in thevertical positioning of the head relative to the head surface that isacceptable for the operation of the system is known as the “z-heightbudget”.

SUMMARY

According to a first aspect of the present invention, there is providedapparatus for attaching a disk to a spindle of a spinstand, theapparatus comprising: a spindle adapter for attaching to a spindle; and,a cap; the spindle adapter having a drawbar movably disposed within, thedrawbar having a connector end that is reversibly connectable to the capand having a piston that is connectable to a source of fluid pressure,the drawbar being movable in response to fluid pressure applied to thepiston so as to urge together the cap and the spindle adapter whenconnected, wherein the cap and the spindle adapter are arranged to becapable of holding a said disk therebetween.

One embodiment provides a way of attaching a disk to a spindle thataddresses the above mentioned problems, and is particularly suited foran inverted spindle and for a manufacturing testing environment where itis desired to swap the disk media being tested as quickly as possible.This arrangement allows the cap to be securely attached to the spindleadapter without the use of bolts, which have a number of disadvantages,and without the use of tools for tightening such bolts. This isparticularly advantageous in a spinstand having an inverted spindle,where there is typically poor access for such tools. (An invertedspindle is a spindle that is mounted in an inverted position, i.e. theend of the spindle to which the disk is mounted is positioned below thebody of the spindle.)

The spindle adapter may have a mating surface for registering with amating surface of the cap when connected and urged together. This allowsa secure connection between the cap and the spindle adapter.

The cap may have a datum surface for registering with a portion of asurface of a said disk. When used with an inverted spindle, thisarrangement is advantageous in that it allows the bottom surface of thedisk, which in this case is the test surface of the disk, to registeragainst a known datum. This known datum is provided since the disk testsurface is registered against a datum surface of the cap and the cap isregistered against a mating surface of the spindle adapter, whichspindle adapter provides a known reference since it is connected to thespindle and thus effectively to the deck itself. This allows theunderside of the disk to be tested in an inverted spindle spinstandwithout the tolerance of the disk thickness affecting the z-height ofthe head relative to the disk test surface.

In an embodiment, the spindle assembly comprises a second pistonconnectable to a source of fluid pressure, the second piston beingarranged to clamp a said disk to the datum surface of the cap inresponse to the fluid pressure. This allows the disk to be securelyreference against the datum surface of the cap. Furthermore, thepressure of the fluid pressure supply can be controlled, therebycontrolling the clamp force acting on the disk. This allows a higherclamp force to be used when accelerating the disk and a lower clampforce when the disk has reached the desired test speed, so that the diskis less likely to suffer from distortion due to excessive clamp force.The clamp force can also be tailored to the disk under test, andparticularly to disks having a variation in their thickness.Furthermore, the clamp force can be lowered to allow the disk to becentred when mounted on the spinstand. Also, the clamp force can becompletely removed to aid disconnection of the cap from the spindleadapter and hence removal of the disk from the apparatus.

In an embodiment, the connector end of the drawbar comprises a latchingassembly for reversibly connecting to the cap. The latching assembly maycomprise a button that is depressible to release the latch. This allowssimple connection and disconnection of the cap to and from the spindleassembly, and thereby connection and disconnection of the disk to theapparatus, without the need for tools. This arrangement is also simplefor the operator to load/unload the disk where an inverted spindle isused and access to the disk is limited. This arrangement also lendsitself to automation of the disk load and unload process.

In an embodiment, the latch button has a camming surface for engagingwith at least one ball bearing of the latching assembly, the latchbutton being biased to cam the at least one ball bearing to a lockingposition in which the at least one ball bearing bears against an edge ofthe cap to hold the cap on the drawbar. In an embodiment, the latchbutton is depressible to allow the at least one ball bearing to moveaway from its locking position so as to allow the cap to disconnect fromthe drawbar.

In an embodiment, the cap has three conical pins arranged to centre asaid disk when placed thereon. This allows the disk to be centred whenplace on the cap.

In an embodiment the apparatus is combined with a spindle, the spindlehaving an inverted configuration.

According to a second aspect of the present invention, there is provideda method of loading a disk to a spindle of a spinstand, the methodcomprising: placing the disk on a cap; applying fluid pressure to apiston of a drawbar of a spindle adapter connected to the spindle tomove the drawbar to a connecting position; connecting the cap to thedrawbar; and, applying fluid pressure to the piston of the drawbar tourge the cap and the spindle adapter together.

The step of disconnecting the cap to the drawbar may comprise:depressing a latch release button of a latch assembly of the drawbar;and, withdrawing the cap to unlatch from the latch assembly.

The step of connecting the cap to the drawbar may be performed by a diskexchanger, the disk exchanger being attached to or integrally formedwith a movable stage for holding a head to be tested, the movable stagebeing movable to move a said head to be tested to a predeterminedposition relative to the disk when mounted to the spindle, the methodcomprising: moving the movable stage and disk exchanger to a firstposition where the disk exchanger is accessible to an operator; placingthe disk on the cap; and, moving the movable stage and disk exchanger toa second position beneath the spindle, where the cap is connected to thedrawbar of the spindle adapter.

According to a third aspect of the present invention, there is provideda method of unloading a disk from a spindle of a spinstand, the methodcomprising: applying fluid pressure to a piston of a drawbar of aspindle adapter connected to the spindle to move the drawbar to adisconnecting position; disconnecting a cap from the drawbar, the capsupporting the disk; and, removing the disk from the cap.

The step of disconnecting the cap to the drawbar may comprise:depressing a latch release button of a latch assembly of the drawbar;and, withdrawing the cap to unlatch from the latch assembly.

The step of disconnecting the cap from the drawbar may be performed by adisk exchanger, the disk exchanger being attached to or integrallyformed with a movable stage for holding a head to be tested, the movablestage being movable to move a said head to be tested to a predeterminedposition relative to the disk when mounted to the spindle, the methodcomprising: moving the movable stage and disk exchanger to a firstposition beneath the spindle, where the cap is disconnected from thedrawbar of the spindle adapter; moving the movable stage and diskexchanger to a second position where the disk exchanger is accessible toan operator; and, removing the disk from the cap.

According to a fourth aspect of the present invention, there is provideda movable stage movable over a deck of a spinstand for exchanging a diskin a said spinstand, the movable stage comprising a lift stage arrangedto hold a cap with a said disk positioned thereon, the lift stage havingat least one actuator for raising the lift stage so that the cap can beconnected with a spindle adapter of an inverted spindle of a spinstand.

This arrangement has the advantage of using the x-y positioner that ispresent in most spinstands for moving the heads to also move the diskexchanger. This allows the disk loading mechanism to be moved between aload position under the spindle for the automation to load the disk toand unload the disk from the spindle, and a receiver position where theoperator can access the lift stage more easily so as to be able toremove and replace a disk from the apparatus. Using the x-y positionerof the movable stage has the advantage that this positioner is usuallyhighly accurate and already present on the spinstand. Thus highprecision movement of the disk exchanger can be attained with minimaladditional parts being required and thus minimal expense.

The apparatus may comprise a cap receiver for receiving a said cap onthe lift stage and a gripper assembly arranged to releasably hold a saidcap in the cap receiver. This allows the cap to be securely held inplace on the lift stage until the cap has been connected to a spindle,at which point the cap can be released. This arrangement can also aid inremoving the cap from a spindle.

The apparatus may comprise an actuator for pressing a latch releasebutton on a said spindle adapter to disconnect a said cap from a saidspindle adapter.

The movable stage may have a head-receiving portion for receiving aread/write head. This allows dual use of the movable stage in bothpositioning the head to the disk and other locations, and positioningthe disk exchange apparatus. Thus the need to have two expensivepositioning stages is avoided.

The movable stage in an embodiment is a puck that is mounted on an airbearing for movement over a deck.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the present invention will now be described by way ofexample with reference to the accompanying drawings, in which:

FIG. 1 shows a plan view of an example of a spinstand in accordance withan embodiment of the present invention;

FIG. 2 shows a partially sectioned side view of the apparatus of FIG. 1;

FIG. 3 shows a more detailed view of the spindle, spindle adapter andcap of FIG. 1;

FIG. 4 shows a plan view of the disk exchanger of FIG. 1;

FIG. 5 shows a side view of the disk exchanger of FIG. 1;

FIG. 6 shows a sectioned side view of the disk exchanger of FIG. 1; and,

FIG. 7 shows the disk exchanger of FIG. 1 with a disk in place.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, a spinstand 1 comprises a deck 2. The deck 2may be made from granite and may be mounted on isolation mounts (notshown) to isolate the spinstand 1 from external vibrations.

The spinstand 1 has a bridge 3 mounted to the deck 2. The bridge 3supports a spindle assembly 4 for holding a disk 5 to be tested in aninverted configuration, i.e. such that the end of the spindle assembly 4to which the disk 5 is fixed is lowermost. As can best be seen in FIG.2, the spinstand 1 also has a disk exchanger 6. The spindle assembly 4and the disk exchanger 6 will be described further below.

The deck 2 also has a movable stage for holding a read/write head 8 tobe tested. The read/write head 8 is incorporated in a head gimbalassembly (HGA). In one embodiment as shown in the drawings, the movablestage includes or is a puck 7 for holding the head 8 that is supportedon the surface of the deck 2, and is movable by a highly accurate x-ypositional stage 9. The puck 7 is positionable by the x-y positionalstage 9, for example being supported on air bearings (not shown) andhaving linear encoders (not shown) to allow its position to beaccurately determined. The puck 7 is positionable so as to move the head8 to a desired location under the surface of the disk 5 when the disk 5is mounted on the spindle assembly 4. It may also be possible to lockdown the puck 7 and/or the elements of the x-y positional stage 9 to thegranite deck 2 by application of a vacuum in order to prevent movementof the puck 7 when in a desired position. Other arrangements of themovable stage are possible. For example, the head 8 may be held on andsupported by the x-y positional stage 9, rather than being held on andsupported by a puck 7 that is in turn supported by the deck 2 andpositioned by the x-y positional stage 9.

As is conventional in the art, the terms x and y directions as usedherein refer to orthogonal directions parallel to the surface of thedeck 2 and disk 5 (i.e. the horizontal), whereas the term z-directionrefers to the direction perpendicular to the deck 2 and parallel to thespindle 4 (i.e. the vertical). The terms downward or lowered are used torefer to moving perpendicularly toward the deck 2, whereas the termsupward or raised are used to refer to moving perpendicularly away fromthe deck 2. The terms axial and radial are to be taken to be relative tothe spindle shaft 22 of the spindle assembly 4 unless the contextdemands otherwise.

The puck 7 also has an arrangement for loading the head 8 to the testsurface of the disk 5, such that the head 8 can read from and/or writeto a track of test data on the test surface of the disk 5. The puck 7also has an arrangement, such as a nanopositioner on which the head 8 ismounted, for making very fine positional changes of the head 8 relativeto the test track.

Thus the spinstand 1 allows a head 8 to be loaded to the disk 5 and veryfine positioning of the head 8 across the test surface of the disk 5whilst test data is written to and read from the disk 5. The test datacan then be analysed as appropriate to the test being conducted.

FIG. 2 shows a sectional view of the spindle assembly 4. The spindleassembly 4 comprises an air bearing spindle having a fixed outer part 21for attachment to the bridge 3, and a rotatable spindle shaft 22 towhich the disk 5 is attached in use. The spindle assembly 4 is“inverted” in that it is mounted so that the end of the spindle shaft 22to which attachment is made extends below the body of the spindleassembly 4. The spindle assembly 4 has an integral DC brushless motor(not shown) for rotating the spindle shaft 22. The spindle assembly 4also has a plurality of ports 23,24 running axially therethrough, oneport 23 being central and the other ports 24 being circumferentiallyspaced at a given outer radial position. These ports 23,24 allow fluidcommunication through the rotating part of the spindle 22 of for examplea vacuum (negative air pressure) or positive air pressure. Inlets 25,26in the top of the spindle assembly 4 allow fluid communication with therespective ports 23,24.

Referring to FIG. 3, a spindle adapter 40 (also known as a mediaadapter) is connected to the spindle shaft 22. A cap 60 is releasablyconnectable to the spindle adapter 40. The disk 5 is held between thespindle adapter 40 and the cap 60 as will be described in the following.

The spindle adapter 40 has a cavity 45 in which a drawbar 41 is movablydisposed. The drawbar 41 has generally an extended cylindrical shape,the axis of which is co-linear with the rotational axis of the spindleadapter 40 and spindle shaft 22. The end portion 42 of the drawbar 41extends beyond the bottom surface 43 of the spindle adapter 40. Thedrawbar 41 also has a piston 44 in the form of a radially extendingflange along the body of the drawbar 41 attached to it or integrallyformed with it.

The drawbar piston 44 has a pressure chamber 45 a beneath it. O-ringseals 46 seal the pressure chamber 45 a to the drawbar 41 and piston 44.The pressure chamber 45 a is in fluid communication with ports 47 in thespindle adapter 40. When the spindle adapter 40 is connected to thespindle shaft 22, these ports 47 are aligned with and in fluidcommunication with the outer ports 24 in the spindle shaft 22. Thusfluid pressure can be supplied to inlet 26 of the spindle 4, via ports24,47 to the pressure chamber 45 a and thereby to the piston 44. Thus byapplying positive fluid pressure, such as pneumatic pressure to inlet24, the piston 44 and drawbar 41 are forced upwards, and by applyingnegative fluid pressure (i.e. a vacuum) to inlet 24, the piston anddrawbar 41 assembly are forced downwards.

The end portion 42 of the drawbar 41 incorporates a ball-latch connector50 for connecting the cap 60 to the drawbar 41. The connector 50comprises a plurality of ball bearings 54 housed in the drawbar 41. Theball bearings 54 are arranged such that they can move between a radiallyextended position where they project beyond the sides of the drawbar 41through holes in the wall of the drawbar 41, and a radially retractedposition where they retract into the body of the drawbar 41 so as not toproject from the drawbar 41.

The connector 50 also comprises a latch release button 51 which isdisposed in a recess in the end of the end portion 42 of the drawbar 41.The button 51 is biased axially downward by a spring 52. The button 51has an upper conical portion 51 a, and a lower shaft portion 51 b ofreduced diameter. When the latch release button 51 is in its lowermostposition, the conical portion 51 a cams the ball bearings 54 to theirextended position. When the latch release button 51 is depressed againstthe action of the biasing spring 52 by pressing on the shaft portion 51b, the ball bearings 54 can fall inward to their retracted positionwithin the drawbar 41.

The cap 60 has a hollow collet 61 at its centre. The interior of thecollet 61 has a smaller diameter portion at one end forming a detentedge 62 or shoulder.

In order to connect the cap 60 to the spindle adapter 40, the latchrelease button 51 is first depressed so that the ball bearings 54 fallinward to their retracted position. The drawbar 41 is in its relaxedposition during this process. Next, the cap 60 with a disk supportedthereon is offered up to the spindle adapter 40, with the connector part50 of the drawbar 41 being accepted into the hollow collet 61. The cap60 is advanced until a mating surface 63 of the cap 60 registers orabuts with a mating surface 43 of the spindle adapter 40, whereupon thecap 60 is fully advanced. This mating of surfaces 43,63 takes placethrough the centre hole in the disk 5. At this position, the upwardlyfacing end of the collet 61 engages with a cooperating recess 43 a inthe mating surface 43 of the spindle adapter 40 so as to keep the cap 60centred on the spindle adapter 40. Also at this position, the ballbearings 54 below the detent edge 62 of the collet 61. The latch releasebutton 51 is then released so that the ball bearings 54 are cammedoutward to their extended position by the conical portion 51 a. At thispoint, the ball bearings 54 prevent the cap 60 from detaching from thedrawbar 41, thus holding the cap 60 in position on the drawbar 41.

Once the cap 60 is connected to the drawbar 41 in this way, fluidpressure is applied to the inlet 26 of the spindle assembly 4 in orderto draw up the drawbar 41. This has the effect of first engaging andthen urging the ball bearings 54 against the detent edge 62 of thecollet 61 and then in turn, engaging and urging the mating surface 63 ofthe cap 60 against the mating surface 43 of the spindle adapter 40. Onceall of the play between components has been taken up, this provides atightly registered connection between the cap 60 and spindle adapter 40.

In order to release the cap 60 from the spindle adapter, the fluidpressure to the inlet 26 is removed. The latch release button 51 is thendepressed to allow the ball bearings 54 to move inward to theirretracted position and the cap 60 is allowed to separate from thespindle adapter 40.

Thus this arrangement allows the cap 60 to be easily and quickly securedto and released from the spindle adapter 40 without using bolts or toolsand the disadvantages associated therewith.

In spinstands in general, the read/write head is usually tested in aninverted position, i.e. the head is held so as to be pointing upwards.This means that it is the bottom surface of the disk under test that iswritten to and read from by the head. This makes controlling thez-height of the test surface of the disk relatively straightforward whena non-inverted spindle configuration is used. The bottom surface of thedisk is clamped against the spindle (via the spindle adapter), whichprovides the known z-height reference or datum. Thus the bottom surface,i.e. the test surface, is directly referenced against the datum.

However, controlling the z-height is more challenging in an invertedspindle configuration. This is because in this configuration it is thetop surface 10 a of the disk 5 that is connected against the spindle 4,the spindle 4 giving the known reference point or datum in thez-direction. However, it is the bottom surface 10 b of the disk 5 thatis tested, i.e. the opposite surface to the one referenced against thedatum. This creates a problem in that the tolerance in the thickness ofthe successive disks 5 being tested greatly affects the z-height of thetest surface 10 b of the disk 5 under test. In fact, currently thetolerance in disk thicknesses is several times the acceptable z-heightbudget.

To address this potential problem, the spindle adapter 40 is providedwith an annular piston 55 being movable in a recess 56 within thespindle adapter 40. The piston 55 is sealed with the walls of the recess56 by O-rings 57 thereby creating a pressure chamber 56 a behind thepiston 55. The pressure chamber 56 a is in fluid communication with aport 58 running through the centre of the drawbar 41 and exiting throughthe side wall of the drawbar 41. The port 58 in the body of the drawbar40 is in fluid communication with the central port 23 of the spindleshaft 22 which in turn is in fluid communication with the inlet 25 inthe spindle assembly 4. O-rings 59 are used to seal the port 58 to thepressure chamber 56 a. Thus, by supplying positive fluid pressure to theinlet 25, fluid pressure is applied via the ports 23,58 to pressurechamber 56 a. This pressure causes the piston 55 to be lowered to engagethe top surface of the disk 5 close to its inner diameter and to urge orclamp the disk 5 against a datum surface 64 of the cap 60. In thisexample the datum surface 64 is the same as the mating surface 63 of thecap 60.

Thus the test surface (i.e. the lowermost surface) of the disk 5 is madeto register against the top surface 63,64 of the cap 60, which in turnis made to register against the spindle adapter 40. In effect then, thetest surface of the disk 5 is made to register against the spindleadapter 40 (via the cap 60), which spindle adapter 40 provides a knownz-height datum. Thus, the tolerance of the thickness of the disk 5 isremoved in determining the z-height of the test surface of the disk 5relative to the head 7.

Another advantage of this clamping arrangement is that the clampingforce delivered to the disk 5 is independent of the thickness of thedisk 5. Thus, the tolerance of the thickness of the disk 5 does notaffect the clamping force. Also, this allows the same spindle adapter 40to be used for different classes of disk 5.

Another advantage of this clamping arrangement is that, by varying thefluid pressure supplied to piston 55, the clamping force applied to thedisk 5 between the piston 55 of the spindle adapter 40 and the datumsurface 64 of the cap 60 can be controlled as required. Again, theclamping force achieved is independent of the thickness of the disk 5.In all cases, whatever the clamping force applied, the test surface 10 bof the disk 5 will be registered against the datum surface 64 of the cap60.

This allows a testing technique where greater clamping force can beapplied to the disk 5 during acceleration of the disk 5 to test speed.This helps prevent slippage of the disk 5 in the adapter 40 due to thehigh torques required during acceleration. This in turn prevents thedamage to the disk 5 that typically occurs when the disk 5 slips.Examples of minimum clamping pressures/axial loads for various diskaccelerations are as follows:

12 krpm/s—26 N axial load or 1.4 Bar (approx. 145 kPa) clamp pressure

15 krpm/s—33 N axial load or 1.8 Bar (approx. 185 kPa) clamp pressure

18 krpm/s—44 N axial load or 2.3 Bar (approx. 235 kPa) clamp pressure.

Once the disk 5 has reached the desired rotational speed for testing,less torque is required and the clamping force can accordingly bereduced whilst testing is carried out. This minimises the possibility ofdisk 5 distortion due to a high clamping force. This is desirable, sincedisk distortion will negatively affect the accuracy of the test results.Also, in a disk test apparatus 1 the disk 5 under test will beultimately intended for incorporation into a head disk assembly and sodistortion to the disk 5 is highly undesirable.

This arrangement of the clamping piston 55 also allows the disk 5 to becentred even when mounted to the spindle 4. To do this, the clampingforce is reduced still further, to nothing or substantially nothing, andthe disk 5 is centred in the adapter 40, for example by tapping an edgeof the disk 5. Thus for example the disk 5 can be centred relative tothe spindle 4 without having to remove the spindle adapter 40 from theapparatus 1, or without having to apply any tools for loosening boltsetc.

Turning to FIGS. 4, 5 and 6, detailed views of the automated diskexchanger 6 are shown. The disk exchanger 6 comprises a base 79 and alift stage 80. The lift stage 80 has a cap receiver 80 a positioned onits uppermost surface for receiving a cap 60. The base 79 has twopneumatic lifters 81 a,81 b by which the lift stage 80 can be raised.The disk exchanger 6 also has two gripper arms 82 a,82 b which areattached to the lift stage 80 and thus are also raised by the lifters 81a,81 b with the lift stage 80.

The ends of the gripper arms 82 a,82 b extend adjacent the cap receiver80 a on opposite sides. The gripper arms 82 a,82 b have inwardlyprotruding blades 83 a,83 b at their ends. The gripper arms 82 a,82 bare pivotably mounted to the lift stage 80 by a pivot 84 and can beactuated to pivot inwards by an actuator 85. When actuated inwards, theprotruding blades 83 a,83 b pass through respective holes 80 b in thesides of the cap receiver 80 a and, when a cap 60 is in the cap receiver80 a, engage with respective recesses 65 in the sides of the cap 60. Inthis position, the gripper blades 83 a,83 b securely hold the cap 60 inplace within the cap receiver 80 a. To release the cap 60 so that it canbe removed from the cap receiver 80 a, the gripper arms 82 a,82 b areactuated outwards so as to withdraw the gripper blades 83 a,83 b fromthe recesses 65 in the sides of the cap 60.

As can best be seen in FIG. 7, the cap 60 has three cylindrical pins 66projecting upward from its datum surface 64. These pins 66 are spaced sothat they pass through the centre of the disk 5 when the disk 5 isplaced on the cap 60, thereby centring the disk 5 on the cap 60 andretaining the disk 5 on the cap 60 when the disk exchanger 6 is beingmoved around as will be discussed below. FIG. 7 shows the disk 5 inposition on the cap 60.

As can also be seen from FIG. 7, the disk exchanger 6 of this embodimentis connected to the puck 7. Thus, the x-y positioner 9 of the puck 7 canbe used to move the disk exchanger 6. The disk exchanger 6 may be movedon an air bearing if desired and/or may be capable of being locked downto the deck 2. The disk exchanger 6 can be moved by the x-y positioner 9from a load position underneath the spindle assembly 4 to a receivingposition away from the bridge 3, where the lift stage 80 is more easilyaccessible by an operator for removing the disk 5 from the cap 60 andplacing a new untested disk 5 in its place.

When the disk exchanger 6 is in position below the spindle adapter 40,by actuating the pneumatic lifters 81 a,81 b to raise the lift stage 80,the cap 60 and disk 5 are offered up to the spindle adapter 40 so thatconnection can be made between them. The lift stage 80 has a furtheractuator 86 (shown in FIG. 6) arranged to depress the latch releasebutton 51 of the spindle adapter ball-latch connector 50 by pressing onthe shaft portion 51 b of the latch release button 51 which protrudesbeneath the cap receiver 80 a through a hole in the centre of the capreceiver 80 a.

Optionally the spinstand may have a disk flutter control device (DFCD)(not shown). The DFCD is a flat block of material of for examplestainless steel or nickel-plated aluminium alloy which is positionedvery close to the upper surface 10 a of the disk 5 during testing, andhelps to reduce vibrations of the disk 5 when it is spun. The DFCD canbe raised and lowered by a pneumatic device (not shown).

Thus the following sequence of actions takes place for loading a disk tothe spindle, some of which may be simultaneous or in a slightlydifferent order:

1. A disk 5 is placed on the cap 60 on the disk exchanger 6 and the puck7 is moved by its x-y positioner 9 so that the cap 60 is under thespindle adapter 40.

2. The DFCD is raised. This ensures that if the disk 5 has not beenplaced flat on the cap 60 and is sloping somewhat it will not contactthe DFCD when the disk 5 is raised by the lift stage 80.

3. The drawbar 41 is lowered and the lift stage 80 of the disk exchanger6 is raised.

4. The connector assembly 50 of the drawbar 41 enters the collet 61, andthe latch button 51 is pressed upwards by the actuator 86 in the liftstage 80. The ball bearings 54 of the connector assembly 50 fall inwardsso that the ball bearings 54 can pass the detent edge 62 in the collet61.

5. The latch button 51 is released and is urged downwards by the biasingspring 52 so that the ball bearings 54 of the connector 50 engage withthe detent edge 62. 6. The gripper arms 82 a,b are pivotted outwards torelease the cap 60. 7. The drawbar 41 is raised by pneumatic pressure onthe piston 44, which urges the cap 60 and the spindle adapter 40together. 8. The DFCD is lowered. 9. The lift stage 80 is lowered. 10.High positive pressure is applied via piston 55 to clamp the disk 5between the piston 55 and the datum surface 64 of the cap 60 so that noslipping occurs due to the high acceleration torque applied to the disk5. 11. The spindle motor starts and brings the disk 5 up to speed. 12.The clamping pressure is reduced to the level appropriate for testing.13. The puck 7 is moved so that the head 8 is under the correct track ofthe disk 5, and testing can take place.

To remove a disk 5 from the spindle adapter 40 the following sequence ofactions takes place, some of which may be simultaneous or in a slightlydifferent order. (It is assumed that that the spindle shaft 22 hasstopped rotating, or that it stops during the first action.)

1. The puck 7 is moved by its x-y positioner 9 so that the diskexchanger 6 is under the spindle adapter 40. 2. The DFCD is raised. 3.The disk clamping pressure is removed. 4. The drawbar 41 is lowered andthe lift stage 80 is raised. 5. The gripper arms 82 a,82 b engage withthe cap 60. 6. The latch button 51 is pressed upwards by the actuator 86in the lift stage 80. The ball bearings 54 of the connector 50 fallinwards so that the end of the drawbar 42 can be withdrawn past theshoulder 62 of the cap 60. 7. The lift stage 80 is lowered, carrying thecap 60 and disk 5 with it. 8. The puck 7 is moved by its x-y positioner9 to place the disk exchanger 6 at the receiving station.

Thus by supplying appropriate control signals to the various actuatorsand sources of fluid pressure hereinbefore described, for exampleco-ordinated by a computer or microcontroller, the exchange of disks 5on the spindle 4 can be performed automatically except for an operatorhaving to remove a tested disk 5 from the disk exchanger 6 and place anew disk 5 in its place when the disk exchanger 6 is in the receiverposition.

Embodiments of the present invention have been described with particularreference to the example illustrated. However, it will be appreciatedthat variations and modifications may be made to the examples describedwithin the scope of the present invention. For example, the invention isnot limited to the specific spindle types or arrangements, or puckpositioning devices specifically described in the description.

1. Apparatus for attaching a disk to a spindle of a spinstand, theapparatus comprising: a spindle adapter for attaching to a spindle; and,a cap; the spindle adapter having a drawbar movably disposed within, thedrawbar having a connector end that is reversibly connectable to the capand having a piston that is connectable to a source of fluid pressure,the drawbar being movable in response to fluid pressure applied to thepiston so as to urge together the cap and the spindle adapter whenconnected, wherein the cap and the spindle adapter are arranged to becapable of holding a said disk therebetween.
 2. Apparatus according toclaim 1, wherein the spindle adapter has a mating surface forregistering with a mating surface of the cap when connected and urgedtogether.
 3. Apparatus according to claim 1, wherein the cap has a datumsurface for registering with a portion of a surface of a said disk. 4.Apparatus according to claim 3, wherein the spindle assembly comprises asecond piston connectable to a source of fluid pressure, the secondpiston being arranged to clamp a said disk to the datum surface of thecap in response to the fluid pressure.
 5. Apparatus according to claim1, wherein the connector end of the drawbar comprises a latchingassembly for reversibly connecting the cap to the drawbar.
 6. Apparatusaccording to claim 5, wherein the latching assembly comprises a latchbutton that is depressible to release the cap.
 7. Apparatus according toclaim 6, wherein the latch button has a camming surface for engagingwith at least one ball bearing of the latching assembly, the latchbutton being biased to cam the at least one ball bearing to a lockingposition in which the at least one ball bearing bears against an edge ofthe cap to hold the cap on the drawbar.
 8. Apparatus according to claim7, wherein the latch button is depressible to allow the at least oneball bearing to move away from its locking position so as to allow thecap to disconnect from the drawbar.
 9. Apparatus according to claim 1,wherein the cap has three conical pins arranged to centre a said diskwhen placed thereon.
 10. Apparatus according to claim 1 in combinationwith a spindle, the spindle having an inverted configuration.
 11. Amethod of attaching a disk to a spindle of a spinstand, the methodcomprising: placing the disk on a cap; applying fluid pressure to apiston of a drawbar of a spindle adapter connected to the spindle tomove the drawbar to a connecting position; connecting the cap to thedrawbar; and, applying fluid pressure to the piston of the drawbar tourge the cap and the spindle adapter together.
 12. A method according toclaim 11, the step of connecting the cap to the drawbar comprising:depressing a latch release button of a latch assembly of the drawbar;and, advancing the cap and releasing the latch release button to causethe cap to latch with the latch assembly.
 13. A method according toclaim 11, wherein the step of connecting the cap to the drawbar isperformed by a disk exchanger, the disk exchanger being attached to orintegrally formed with a movable stage for holding a head to be tested,the movable stage being movable to move a said head to be tested to apredetermined position relative to the disk when mounted to the spindle,the method comprising: moving the movable stage and disk exchanger to afirst position where the disk exchanger is accessible to an operator;placing the disk on the cap; and, moving the movable stage and diskexchanger to a second position beneath the spindle, where the cap isconnected to the drawbar of the spindle adapter.
 14. A method accordingto claim 13, wherein the movable stage is a puck that is mounted on anair bearing for movement over a deck.
 15. A method of detaching a diskfrom a spindle of a spinstand, the method comprising: applying fluidpressure to a piston of a drawbar of a spindle adapter connected to thespindle to move the drawbar to a disconnecting position; disconnecting acap from the drawbar, the cap supporting the disk; and, removing thedisk from the cap.
 16. A method according to claim 15, the step ofdisconnecting the cap to the drawbar comprising: depressing a latchrelease button of a latch assembly of the drawbar; and, withdrawing thecap to unlatch from the latch assembly.
 17. A method according to claim15, wherein the step of disconnecting the cap from the drawbar isperformed by a disk exchanger, the disk exchanger being attached to orintegrally formed with a movable stage for holding a head to be tested,the movable stage being movable to move a said head to be tested to apredetermined position relative to the disk when mounted to the spindle,the method comprising: moving the movable stage and disk exchanger to afirst position beneath the spindle, where the cap is disconnected fromthe drawbar of the spindle adapter; moving the movable stage and diskexchanger to a second position where the disk exchanger is accessible toan operator; and, removing the disk from the cap.
 18. A method accordingto claim 17, wherein the movable stage is a puck that is mounted on anair bearing for movement over a deck.
 19. A movable stage movable over adeck of a spinstand for exchanging a disk in a said spinstand, themovable stage comprising a lift stage arranged to hold a cap with a saiddisk positioned thereon, the lift stage having at least one actuator forraising the lift stage so that the cap can be connected with a spindleadapter of an inverted spindle of a spinstand.
 20. A movable stageaccording to claim 19, comprising a cap receiver for receiving a saidcap on the lift stage and a gripper assembly arranged to releasably holda said cap in the cap receiver.
 21. A movable stage according to claim19, comprising an actuator for pressing a latch release button on a saidspindle adapter to disconnect a said cap from a said spindle adapter.22. A movable stage according to claim 19, wherein the movable stage hasa head-receiving portion for receiving a read/write head.
 23. A movablestage according to claim 19, wherein the movable stage is a puck that ismounted on an air bearing for movement over a deck.
 24. A spinstandcomprising apparatus according claim 1, a spindle to which the spindleadapter is attached, a deck, and a movable stage according to claim 19positionable over said deck.